中文摘要：

在金电极表面修饰壳聚糖（CS）膜，并在酸性pH下利用CS上形成的-NH3^＋静电吸引Fe（CN）6^3-（FeCN）到电极表面，制成了在pH6．5磷酸盐缓冲液（PBS）中具有电活性的Au｜CS-FeCN电极；再通过外加磁场吸引，在Au｜CS-FeCN表面修饰一层血清癌抗原19—9单克隆抗体（anti CA19—9）包被的金磁纳米微粒（Fe3O4（核）／Au（壳），简称GMP），由此构建了一类快速检测CA19—9的无试剂安培免疫传感器（Au｜CS-FeCN／GMP-anti CA19—9）。用扫描电镜（SEM）、X-射线荧光光谱（XFS）和X-射线光电子能谱（XPS）对电极表面进行了表征；并采用循环伏安法（cV）、示差脉冲伏安法（DPV）、交流阻抗法（EIS）分别研究了该传感器的电化学性质和对CA19—9的检测性能。实验表明：Au｜CS-FeCN／GMP-anti CA19—9电极在含CA19—9的pH6．5 PBS中于35℃下温育25min，其DPV还原电流下降值（△I）与CA19—9在0．1～10U／mL和10～50U／mL范围内成正比，检出下限为0．056U／mL（3σ）。用于血清样本检测并和标准ELISA方法对照，结果一致。只需移去外加磁场，用PBS清洗电极表面即可实现电极更新。该磁性免疫传感器集分离、富集和测定于一身，灵敏度高、稳定性好、表面易更新，有望用于人血清中痕量CA19—9的快速检测。

英文摘要：

A novel amperometric immunosensor for human serum carbohydrate antigen 19-9 （CA19-9） based on iis antibody （anti CA19-9） coated Fe3O4 （core）/Au（shell） gold-magnetic nanocomposites（GMP） modified electrode is investigated. Firstly,chitosan（CS） was adsorbed on the surface of Au electrode （Au｜CS）, then Fe （CN） 3 （FeCN） was connected to-NH3^＋ on the surface of chitosan film to form Au｜CS-FeCN electrode by electrostatic attraction in acidic pH. FeCN can be employed as an electron transfer mediator. Furthermore anti CA19-9 coated GMP（GMP-anti CA19-9） was immobilized on the surface of Au｜ CS-FeCN by outside magnetic field adsorption to form one CA19-9 amperometric immunosensor （Au｜ CS-FeCN/GMP- anti CA19-9）. The surface of the modified electrode was characterized by scanning electron microscopy （SEM）, X-ray fluorescence （XFS） and X-ray photoelectron spectrometry（XPS）. Its electrochemical charac- ters were studied by cyclic voltammetry （CV）, differential pulse voltammetry （DPV） and AC impedance （EIS）. In pH 6.5 PBS,after the immunosensor is incubated with CA19-9 solution at 35 ℃ for 25 min,the electron transfer access of FeCN is partly inhibited,which leads to a linear decrease of current. Under optium conditions,the linear range of CA19-9 by the immunosensor is from 0. 1 U/mL to 10 U/mL and 10 U/ mL to 50 U/mL with a detection limit of 0. 056 U/mL estimated at 3 times noise. The immunosensor was employed to determine CA19-9 in human serums and the results were consistent with ELISA method. Moreover,its surface can renew after magnetic field was removed. The immunosensor combines many functions as separation, enrichment and determination in one, with high sensitivity and good stability. This method would be valuable for clinical immunoassay for CA19-9 in human serum.